Apparatus and methods for transmitting an MPEG-information signal and a method for reproducing that signal

Abstract

A method of transmitting timing critical data via an asynchronous channel without changing any datum to be transmitted. The timing critical data can be an MPEG transport stream. The asynchronous channel can be a computer or telephone network, a digital storage media such as a digital VCR, or a digital interface. The method involves tagging each transmission unit of the data stream, before inputting to the channel, with timing information, and using the timing information at the output end of the channel to recreate the proper data timing. Various schemes are described for packing the timing information tags with each or a plurality of transmission units.

What is claimed is:  
     
       1. A method of processing timing-critical data, comprising the steps of: 
       providing the timing-critical data subdivided into an original timing-critical data stream of successive transmission units a plurality of which have critical timing;  
       determining from the original timing-critical data stream, tagging information which is not contained in the transmission units of the original data stream and which is utilized for producing from a transmitted data stream a recreated data stream such that a first relative bitwise timing of the plurality of transmission units in the recreated data stream has been recovered, wherein the transmitted data stream comprises the plurality of transmission units that have passed through an asynchronous channel such that the asynchronous channel changed the relative bitwise timing of the plurality of transmission units from the first bitwise timing to a second bitwise timing;  
       tagging the successive transmission units with the tagging information; and  
       transmitting the transmission units which include the plurality of transmission units and which include the transmission units tagged with the tagging information into the asynchronous channel.  
     
     
       2. The method of  claim 1 , in which the timing-critical data is an MPEG data stream, and the transmission units are MPEG transport packets. 
     
     
       3. The method of  claim 1 , in which the asynchronous channel is a digital VCR. 
     
     
       4. The method of  claim 1 , in which the tagging information includes timing information associated with the plurality of transmission units. 
     
     
       5. The method of  claim 4  in which the timing information includes a beginning time at which the plurality of transmission units are to be supplied in the recreated data stream. 
     
     
       6. The method of  claim 1  in which: 
       the transmission units are of a fixed size and have a fixed transport rate in the original data stream;  
       a transmission unit in the original data stream is not transmitted into the asynchronous channel; and  
       the tagging information includes a sequence number representing the sequential position of a transmission unit relative to the successive transmission units in the original data stream including transmission units which are not transmitted.  
     
     
       7. The method of  claim 4 , in which the timing information includes two items of timing information. 
     
     
       8. The method of  claim 7 , in which the two items of timing information include a beginning time at which each timing-critical transmission unit is to be supplied in the recreated data stream and a duration for which each timing-critical transmission unit is to be supplied in the recreated data stream. 
     
     
       9. The method of  claim 7 , in which the two items of timing information include a beginning time at which each timing-critical transmission unit is to be supplied in the recreated data stream and an ending time for completion of a supplying of the timing-critical transmission unit such that a bit rate for the recreated data stream can be calculated depending on the beginning time and the ending time. 
     
     
       10. The method of  claim 1 , in which tagging information for the plurality of transmission units is stored in a data unit associated with the plurality of transmission units. 
     
     
       11. The method of  claim 10 , in which: the transmission units are stored in the data unit with the associated tagging information; and the plurality of transmission units are 5 in number. 
     
     
       12. The method of  claim 10 , in which the tagging information includes a pointer to a byte location for a transmission unit in the data unit. 
     
     
       13. The method of  claim 12  in which the byte location is the first byte of the transmission unit or the last byte of the transmission unit. 
     
     
       14. The method of  claim 12  in which the transmission unit is an MPEG packet and the byte location in the data unit corresponds to a location reserved for the program clock reference in the packet. 
     
     
       15. The method of  claim 1 , in which the timing-critical data is formatted as a data block in the asynchronous channel, including: a block header; a block payload including the plurality of transmission units and the tagging information; and an error-checking block. 
     
     
       16. The method of  claim 1 , further comprising the steps of: 
       transmitting the at least one transmission unit tagged with the tagging information through the asynchronous channel such that the transmitted data stream is formed from the at least one transmission unit that has passed through the asynchronous channel; and  
       producing, depending on the tagging information, the recreated data stream from the transmitted data stream such that the recreated data stream has recovered the bitwise timing of the original data stream.  
     
     
       17. A method for processing a data stream that has become a transmitted data stream having a second bitwise timing after having been transmitted through an asynchronous channel, wherein prior to being introduced into the asynchronous channel the data stream had a first bitwise timing, and wherein the second bitwise timing differs from the first bitwise timing, comprising: 
       producing, depending on tagging information in the transmitted data stream wherein the tagging information was not contained within the data stream prior to when the data stream was introduced into the asynchronous channel, a recreated data stream from the transmitted data stream such that the recreated data stream has recovered the first bitwise timing.  
     
     
       18. Apparatus for processing timing-critical data, comprising the steps of: 
       means for providing the timing-critical data subdivided into an original timing-critical data stream of successive transmission units a plurality of which have critical timing;  
       means for determining from the original timing-critical data stream, tagging information which is not contained in the transmission units of the original data stream and which is utilized for producing from a transmitted data stream a recreated data stream such that a first relative bitwise timing of the plurality of transmission units in the recreated data stream has been recovered, wherein the transmitted data stream comprises the plurality of transmission units that have passed through an asynchronous channel such that the asynchronous channel changed the relative bitwise timing of the plurality of transmission units from the first bitwise timing to a second bitwise timing;  
       means for tagging the successive transmission units with the tagging information; and  
       means for transmitting the transmission units which include the plurality of transmission units and which include the transmission units tagged with the tagging information into the asynchronous channel.  
     
     
       19. Apparatus for processing a timing-critical data stream that has become a transmitted data stream having a second bitwise timing after having been transmitted through an asynchronous channel, wherein prior to being introduced into the asynchronous channel the data stream had a first bitwise timing, and wherein the second bitwise timing differs from the first bitwise timing, said apparatus comprising: 
       means for receiving the transmitted data stream from the asynchronous channel; and  
       means for producing, depending on tagging information in the transmitted data stream wherein the tagging information was not contained within the data stream prior to when the data stream was introduced into the asynchronous channel, a recreated data stream from the transmitted data stream received from the asynchronous channel such that the recreated data stream has recovered the first bitwise timing.  
     
     
       20. A digital recorder of timing-critical data, comprising: 
       means for providing the timing-critical data subdivided into an original timing-critical data stream of successive transmission units a plurality of which have critical timing;  
       means for determining from the original timing-critical data stream, tagging information which is not contained in the transmission units of the original data stream and which is utilized for producing from a transmitted data stream a recreated data stream such that a first relative bitwise timing of the plurality of transmission units in the recreated data stream has been recovered, wherein the transmitted data steam comprises the plurality of transmission units that have passed through an asynchronous channel such that the asynchronous channel changed the relative bitwise timing of the plurality of transmission units from the first bitwise timing to a second bitwise timing;  
       means for tagging the successive transmission units with the tagging information; and  
       means for channel encoding the tagged transmission units; and  
       means for writing the channel encoded tagged transmission units onto an information carrier in an asynchronous manner, said means for writing including means for transmitting the transmission units which include the plurality of transmission units and which include the transmission units tagged with the tagging information into the asynchronous channel.  
     
     
       21. A digital player of timing-critical data, comprising: 
       means for reading an asynchronous stream of channel encoded timing-critical transmission units tagged with tagging information, from an information carrier;  
       means for channel decoding the tagged transmission units;  
       means for determining times at which to supply the transmission units, depending on the tagging information, wherein the determined times correspond to a first bitwise timing comprised by the stream prior to becoming asynchronous such that the asynchronous stream has a second bitwise timing that differs from the first bitwise timing; and  
       means for supplying the timing-critical transmission units at the determined times as a recreated timing-critical data stream.  
     
     
       22. A record carrier, comprising: 
       a substrate;  
       tracks on the substrate; and  
       information structures stored in the tracks in an asynchronous manner including channel encoded, timing-critical transmission units tagged with tagging information sufficient to supply the timing-critical transmission units at determined times as a recreated timing-critical data stream, wherein the determined times correspond to a first bitwise timing comprised by the transmission units prior to being stored in the tracks, and wherein the transmission units asynchronously acquired a second bitwise timing subsequent to having had the first bitwise timing and prior to being supplied at the predetermined times.